American Fisheries Society

Marine Fisheries Section

MFS Statements:

Marine Fisheries Section 1997 Statement on Bluefin Tuna

Background

            The Marine Fisheries Section (MFS) of the American Fisheries Society has been monitoring the stock condition and management of Atlantic bluefin tuna closely since at least 1991.  Several statements have been issued over this time period by the MFS, which have expressed our concern over the status of the western Atlantic stock and in which we have suggested what we, as professional fishery scientists, believe is appropriate action to rebuild the stock.

            In our first statement, released in May, 1992, we recommended, among other things, that a recovery plan and timetable be implemented immediately.  In a ubsequent statement released in July, 1995, we again stated that "the immediate priority is to define a biologically acceptable recovery target and establish and implement a stringent timetable for rebuilding the stock to this target level. Until such time as the rebuilding plan is implemented by ICCAT and the question of spawning site fidelity is resolved, the MFS believes that quota increases are inappropriate and that the current quota should be maintained or reduced."

            At the 1995 meeting of the International Commission for the Conservation of Atlantic Tunas (ICCAT) the commission approved the following resolution: "That the SCRS develop, at its 1996 meeting, separate and distinct recovery options for each of the western and eastern Atlantic bluefin tuna management stocks, taking into account the possible effects of mixing that may occur; and the SCRS should calculate a series of annual total allowable catches  (TACs) based on stock projections that are needed for rebuilding the western and eastern management stocks, respectively, to levels which would support MSY, within selected alternative recovery time periods and with intermediate goals and milestones along the path to rebuilding.  Therecovery options shall be based on the 1996 stock assessments for each management stock. The selected alternative recovery time periods shall be 10, 15 and 20 years, with a 50% probability."

            The MFS viewed this action by the commission as a positive and decisive step towards the ultimate recovery of the western Atlantic stock of bluefin tuna.  This action, combined with recent ICCAT resolutions authorizing aggressive trade restrictive measures to ensure compliance by both member and non-member nations, was generally recognized as a turning point in the responsiveness and effectiveness of ICCAT.

Recent ICCAT Actions

            The results of the 1996 SCRS stock assessment and recovery projections indicate that a 50% probability of recovery to the MSY biomass level within even the most distant time horizon that the commission wanted to consider (20 years) would require a constant quota of no more than 500 mt. Despite this, the commission approved a quota increase of 150 mt to 2354 mt (2500 mt including discards), with the justification that this catch level is sustainable and that the spawning stock will show a gradual increase over a period of 20 years.  However, the projections also indicate that, while there is virtually no chance that the stock will rebuild to MSY in 20 years, there is a significant chance that the spawning stock will continue to decline. While we recognize that these projections have a great deal of uncertainty associated with them, we believe that quota increases are risk prone and inappropriate considering our current understanding of the stock condition.

Conclusions

            Bluefin tuna have been under some form of active management by ICCAT since 1974 when a minimum size was imposed.  Thus, ICCAT has been managing bluefin for 23 years and the spawning stock is currently at or near its lowest level ever. With the current quota, the spawning stock is projected to increase slightly over the next 20 years, but only to about 25% of the target level after 43 years of management.  The MFS believes that allowing the spawning stock to remain at such low levels for such a protracted period of time places the stock in serious danger of collapse.  Therefore we conclude that the most recent action taken by ICCAT, increasing the quota and failing to define and implement a recovery target and timetable, is inconsistent with our  previous recommendations and inappropriate considering the current understanding of the status of the stock.

            Furthermore, the MFS notes that the question of spawning site fidelity remains unresolved, and again cautions that if bluefin tuna exhibit spawning site fidelity, then current spawning biomass estimates for the western Atlantic could substantially overestimate the true spawning biomass.  The MFS stresses that transatlantic movement of fish in either direction reveals little information about spawning site fidelity unless the natal area of the tagged fish is known or can be inferred. Indices of abundance for the Gulf of Mexico, the principal west Atlantic spawning area, remain at very low levels, suggesting that the true west Atlantic spawning stock may be at substantially lower levels than indicated by the stock assessment.

            The MFS again urges the ICCAT commission to maintain or reduce the quota until such time as a rebuilding plan is implemented and the question of spawning site fidelity is resolved.

Steven A. Berkeley

Hatfield Marine Science Center

2030 Marine Science Drive

Newport, OR 97365

ph. 541-867-0135

fax 541-867-0138